Download INTEROSSEOUS MUSCLE TIGHTNESS TESTING

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2615 London Dr.
Raleigh, NC 27608
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Complex made Simple...clinically relevant education by Judy C. Colditz, OT/L, CHT, FAOTA
May, 2012
No. 19
INTEROSSEOUS MUSCLE TIGHTNESS TESTING
INTEROSSEOUS MUSCLE TIGHTNESS
TESTING - ARE YOU DOING IT CORRECTLY?
The common term “Intrinsic Tightness Testing”
is a misnomer as it describes a maneuver
specifically designed to test tightness of the
interosseous muscles. The interosseous muscles
are small, short-fibered muscles contained within
a fascial compartment between the metacarpals
and are more prone to adaptive shortening in
the presence of edema and limited mobility than
are the slender longer-fibered lumbrical muscles.
Because the origin and the insertion of the
interosseous and the lumbrical muscles differ,
they cannot be tested with the same test. The test
described below should be correctly called the
Interosseous Muscle Tightness Test.
Position for testing interosseous
muscle tightness
TEST MANEUVERS
The Interosseous Tightness Testing was first
described by Finochietto in 1920. It consists of:
1.
Passive flexion of MP and PIP joints of
one finger (with the MP joint in neutral alignment
radially and ulnarly) while observing/measuring
the range of passive PIP joint flexion.
2.
Passive extension of MP joint (with the MP
joint in neutral alignment) with concurrent passive
flexion of the PIP joint while observing/measuring
the range of passive PIP joint flexion.
EXCLUSION OF THE DIP JOINT
In Finochietto’s original article, the DIP joint is
not included in the testing. Since the interosseous
muscles primarily extend the PIP joint through the
oblique fibers which terminate at the central slip
insertion just distal to the PIP joint, flexion of the
PIP joint demands elongation of the interosseous
muscles. Unfortunately, many therapists and
surgeons have been taught to include the DIP joint
in testing, which is an incorrect technique
HOW FAR DO YOU EXTEND THE MP JOINT?
A variable not defined in Finochietto’s
description is the extent of passive MP joint
extension. If you passively hyperextend the
MP joint of a normal mobile finger to absolute
maximum, resistance to passive PIP joint flexion
will be created. Conversely, most of us are able to
actively hyperextend our MP joints while actively
holding our IP joints fully flexed, proving that we
can elongate our interosseous muscles beyond
the position of zero extension at the MP joint. So
what is the ideal position for the MP joint when
testing?
The best solution to this quandary is to carefully
examine the contralateral finger (as long as it is
uninvolved/uninjured) to determine the maximum
passive MP joint extension possible while the PIP
joint is in maximum passive flexion. Although there
is no data that contralateral fingers are the same
in an individual, this nevertheless is the best way
we have to determine the ideal testing position
© HandLab; 2012 all rights reserved
continued...
Disclaimer: HandLab Clinical Pearls are intended to be an informal sharing of practical clinical ideas; not formal evidence-based conclusions of fact.
www.HandLab.com
[email protected]
2615 London Dr.
Raleigh, NC 27608
USA
Complex made Simple...clinically relevant education by Judy C. Colditz, OT/L, CHT, FAOTA
May, 2012
No. 19
INTEROSSEOUS MUSCLE TIGHTNESS TESTING-page 2
for the MP joint for each finger of each patient.
There is a large range of normal among individuals
and an attempt to standardize this position for all
individuals is not realistic. Many clinicians have
been taught to only take the MP joint to a position
of zero degrees extension, which is a sub-optimal
testing position for most individuals and thus can
result in a false negative outcome.
To determine how far to hyperextend the MP
joint of the injured/involved finger, examine the
contralateral uninjured/uninvolved finger:
1.
Simultaneously passively hyperextend the
MP joint to its easy maximum while holding the PIP
joint in its maximum passive flexion. Measure MP
joint hyperextension.
2.
This degree of MP joint hyperextension is
the desired testing position for the MP of the injured
finger.
WHEN IS THE TEST POSITIVE?
The only the question that must be satisfied for
the test to be positive is: “Can less PIP flexion be
demonstrated with the MP extended than with it
flexed?” If you can answer yes, the test is positive.
CAN I TEST FOR INTEROSSEOUS MUSCLE
TIGHTNESS WHEN THE FINGER HAS LIMITED
PASSIVE MOTION?
The common clinical presentation is stiffness of
the entire digit. Interosseous tightness is only one
factor in addition to other soft tissue constraints
such as capsular tightness and tendon adherence.
The examiner may assume that limited passive
motion makes interosseous muscle tightness
testing impossible. In my clinical experience it is
rare that one cannot identify a reduction in PIP
passive flexion when the MP joint extended when
interosseous muscle tightness is present, even in
stiff fingers with limited passive flexion.
In our next Clinical Pearl we will discuss quantifying
interosseous muscle tightness.
REFERENCES/SUGGESTED READING
1. Bunnell S. Ischaemic contracture, local, in the hand. J Bone Joint Surg 1953;35A(1):88-101.
2. Finochietto R. Retracción de Volkmann de los músculos intrínsecos de las manos. Bol Trab Soc Cir,
Buenos Aires 1920;4:31.
© HandLab; 2012 all rights reserved
Disclaimer: HandLab Clinical Pearls are intended to be an informal sharing of practical clinical ideas; not formal evidence-based conclusions of fact.